Fluid transfer hose products that are used in numerous applications to convey media that may be corrosive, caustic, or food grade, are typically exposed to a variety of deleterious and harmful conditions including extreme pressures, temperatures and flexing. The types of media being conveyed and the conditions to which the hose product will be exposed have led to the design of hose products having multiple layers. The materials of each layer have specific, and preferably complementary properties. Inner layers, for example, are typically designed to be chemically inert and resistant to permeation by liquids and gases, while outer layers possess mechanical strength and shock and abrasion resistance.
Due to the ever-increasing demands placed on fluid transfer hose products, continuous efforts directed toward improving the properties of these products have been undertaken by the hose industry.
Prior art attempts to reduce permeation in multi-layer smooth bore hose assemblies having one or more fluoropolymer layers include increasing wall thicknesses, using higher grade polymers, and processing polymers to have increased crystallinity. Unfortunately, increasing the wall thickness decreases the flexibility of the finished product as well as increasing its weight and cost. Using higher-grade polymers also increases the cost of the finished product, while increasing crystallinity increases the flexural modulus of the material thus decreasing the flexibility and reducing flex life.
Moreover, producing convoluted or corrugated hose constructions for applications requiring higher levels of flexibility in addition to permeation resistance has proven very difficult. Indeed, it has been commonly held that many convoluted hose constructions would not be suitable for such applications because the “thinning” of the walls to produce “flex” was expected to result in increased permeation to fluids.
A need therefore exists for a fluid transfer hose construction having improved barrier properties.
It is therefore a primary object of the present invention to provide such a hose construction.
It is a more particular object to provide a laminated hose construction having one or more intermediate metal barrier layers that exhibits good bond strength between layers, improved barrier properties and improved durability.
It is yet a more particular object to provide a convoluted, laminated hose construction having one or more intermediate metal barrier layers that demonstrates higher levels of flexibility in addition to the above-noted properties.